The present invention relates to a method of and a system for selecting, at application of Continuous Data Protection (CDP), storage volumes to store copy data and update requests.
A storage system includes at least one volume and may also include a plurality of volumes having different physical characteristics.
The continuous data protection system continuously protects data stored in volumes in the storage system. Specifically, the continuous data protection system includes a function to read data from a volume (a protection target volume) designated as a target of continuous data protection and to store the data in a volume (a copy data storage volume) designated as a storage destination of copy data, a function to store an update request of data for the protection target volume in a volume (an update request storage volume) designated as a storage destination of the update request, and a function to update the copy data in the copy data storage volume by storing, according to a designated condition, the update request to be stored in the update request storage volume in the copy data storage volume. The system also includes a function which updates the copy data in the copy data storage volume by use of update requests in the update request storage volume to restore data in the protection target volume to a predetermined position of the update requests stored in the update request storage volume.
JP-A-2005-18738 describes an example of implementation of continuous data protection, specifically, a relationship between a function (a snapshot function) to store data in a protection target volume at a point of time in a copy data storage volume and a function (a journal entry function) to store an update request of data in an update request storage volume. It is predicted that quite a large number of journal entries are to be handled. To cope with this difficulty, if the number of unused areas of the update request storage volume is less than a limit value, the journal entries are updated onto the snapshot.
JP-A-2006-134323 describes a method of deriving the capacity and processing performance of a journal volume according to a Recovery Point Objective (RPO) and a Recovery Time Objective (RTO) designated by the user.